How to Protect a Network Against Lightning? 120
RichiH asks: "The monsoon, started about a month early in India this year. While it is not sure if that is due to global warming or not, there are more pressing issues for the IT world at hand. Until about the end of July, there will be major thunderstorms in this area. How do you protect a network that is spread over 100 square kilometres in a land where the concept of a lightening arrestor is next to unknown? The network in question consists of about 2500 boxes of various kinds which are connected using 10BASE2 (aka BNC), 10BASE-T (aka RJ45) and 10BASE5 (aka thicknet), where only the last one may be new to some readers. The big question is: how can you protect yourself against these storms in a way that is both fast to implement and does not require laying of new lines?"
Lightning protection (Score:3, Informative)
Re:Lightning protection (Score:2)
Re:Lightning protection (Score:1)
Re:Lightning protection (Score:2)
Given this, I recommend you liberally wrap all the buildings in a highly conductive material such as copper or aluminum foil and perhaps put a nice big electricity conducting rod on top of that to try to attract the ele
Enormously Controversial (Score:4, Informative)
Two words, lightning rod.
Actually, among people who care about these sorts of things [and there are precious few in this business who give a damn], lightning rods, and, more generally, good grounding, are enormously controversial.
Classically, the thinking was that a well grounded lightning rod served to divert voltage surges away from the interior of your structure and down to the groundwater, or, more specifically, to the ionized particles suspended in moist soil. [Oh, and, by the way, once the surge makes it to "groundwater," there's no guarantee it'll stay there; it's entirely possible that it'll decide it doesn't like groundwater and find an alternate route back into your structure. These phenomena generally fall under the title of "grounding loops."]
However, there's a new school of thought which holds that a well-grounded lightning rod serves to ATTRACT voltage surges, and could cause a voltage surge to get nearer to your structure than would otherwise be the case. If you follow that approach, you want safety in numbers: You hope that there are enough targets out there that are well enough grounded that the voltage surge will be diverted towards them, rather than towards you.
If you're interested in residential and light-commercial products, I can highly recommend the surge protectors of Panamax; in particulary, we've had a lot of luck with their Max 8 Coax product shielding broadband over coaxial cable:
The Panamax products tend to work interior to a building. [By the way, as far as interior wiring is concerned, did you know that in three-color wiring, the white wire and the bare wire are connected to the same mount in your circuit breaker box? I.e., once you get inside a building, white and ground are one & the same.] For products exterior to a building, I'd take a look at Citel, of Miami, FL [especially their P8AX series for coaxial cable lines, although they have myriad products for POTS and CAT5, as well]:clarification (Score:1)
the white wire and the bare wire are connected to the same mount in your circuit breaker box
A few years ago, there was a change in the code, which now requires white and ground to be anchored to two different mounts, but in almost all existing construction, that won't be the case.
Re:clarification (Score:2)
Re:Enormously Controversial (Score:2)
The way a lightning rod works is that it provides a highly conductive path to ground that drains off charge (shorts it to ground, so to speak) before that charge builds up enough to achieve the difference in potential necessary for a lightning bolt. If the end that points up comes to a sharp point it does this better than if that end is rounded.
The lightning rod is, of course, grounded, usually with very heavy gauge (i.e., low, low resistance) wire connecting it to a ground rod.
Re:Lightning protection (Score:2)
Install lightning rods on OTHER tall buildings within a 250-1000 metre radius of the building to be protected.
Make sure that lightning rods + buildings end up much taller than the building to be protected.
Easy solution... (Score:5, Funny)
Outsource it back to the US (Score:2)
Re:Outsource it back to the US (Score:2)
Not much help to you, but it tells you about the frequency of Florida Lightning.
Re:Outsource it back to the US (Score:2)
WiFi (Score:4, Informative)
Re:WiFi (Score:2)
Re:WiFi (Score:1)
Re:WiFi (Score:2)
Re:WiFi (Score:2)
Great Scott, son, we're talking 1.21 JIGGA-watts here!
Re:WiFi (Score:2)
Re:WiFi (Score:2)
Best thing for lightning, don't want it blown, do
Re:WiFi (Score:2, Informative)
Rf is basically AC current going thru the air.
E=I*R, so, I=E/R
E=the RF you transmit
R=resistance of transmission media
Since E isn't zero, and R isn't infinite, then there must be current (I) somewhere.
WiFi-Clearing the air. (Score:1, Informative)
AC (Alternating Current) isn't the same thing as RF (Radio Frequency). Two the levels are so low that it's effectively irrelivent. Now if the RF energy was ionizing the air, you might have a path, but even TV stations don't do that.
Poster two [slashdot.org]
"All except for that great big metal and plastic rod sticking up that we call an antenna..."
Not all antennas "stick up", and there are ways to minamize the effects of "sticking up". Remember lightening rods, and antennas work bec
Re:WiFi (Score:5, Informative)
Re:WiFi (Score:1)
There are proper ways to protect a network against lightning, and there are halfass "solutions" like these. Make sure you do your research before choosing eithe
Re:WiFi (Score:3, Interesting)
s/several/all/
Picture a lightning bolt. It's white, right? White is the sum of all colors. White (RF) noise is the sum of all frequencies.
Huh... (Score:4, Funny)
Actually, the safest way to protect your equipment against lightning strikes is wire a lightning rod directly into your network's central switch. The extra voltage and current from the lighting will safely disperse through all the attached systems, and you may even notice an increase in performance!
Don't let anyone tell you otherwise.
Huh...Shock and awe. (Score:3, Informative)
Re:Huh...Shock and awe. (Score:2)
Re:Huh...Shock and awe. (Score:1)
Re:Huh...Shock and awe. (Score:3, Funny)
Re:Huh... (Score:2)
to obvious? (Score:4, Funny)
Like, you know, at the time of installing the network?
just asking, what do I know about stuff like this...
Re:to obvious? (Score:2)
Like, you know, at the time of installing the network?
just asking, what do I know about stuff like this...
Since the network includes thicknet and BNC cabling, it's probably a mishmash of systems that's been pieced together over at least 20 years. It's probably been struck by lightning a few times, and only now do they have someone interested in minimizing damage.
Wireless bridges? (Score:2)
Lightning (Score:3, Informative)
802.11 + a Pringles can!
The only reliable way to control lightning (Score:3, Funny)
Cheap Hardware (Score:5, Interesting)
Re:Cheap Hardware (Score:2)
High voltage HATES inductance. One large diameter turn of the cable after the spark gap and the high voltage will absolutely refuse to take the extra millisecond required to build up the huge magnetic field around the coil.
Zounds! (Score:5, Funny)
Geeks these days...
Re:Zounds! (Score:1)
And Raise Dead is a 5th level Cleric spell. Why bother continuously protecting against something that might happen occasionally, when it's just easier to fix the results after the fact? (Now if only there were a Raise Charred Metal spell...)
Re:Zounds! (Score:1)
Just get a lich or some master dwarves or something, I'm sure one of them will make a computer golem for you.
Re:Zounds! (Score:1)
Somehow, I'm not really thrilled at the thought of my Windows Media Player punching me in the face for 2d8+12 points of damage whenever I play an MP3 file for which I don't have a valid certificate.
Just get a lich or some master dwarves or something, I'm sure one of them will make a computer golem for you.
I assume that you've never worked in the HR department of a company that has had a disgruntled lich on the payroll.
Re:Zounds! (Score:2)
Not if you're a dead 5th level Cleric.
how (Score:2, Funny)
Here is an extract from the concluding part:
"After carefull research we are now convinced that the solution to the problem was: roof."
Mitigation (Score:3, Informative)
be practical. What you want is to minimize the amount of stuff (equipment,
data,
your network into segements in such a way that data can travel between the
segments but lightning won't. Wireless is one option, but I think there are
other ways to accomplish this. Some UPSes have data line protection...
Then there's data. One word: backups.
Fiber (Score:5, Insightful)
That's a good idea regardless of lightning, simply because ground isn't quite the same from building to building. (Or sometimes even from outlet to outlet.)
Re:Fiber (Score:4, Insightful)
Once you are inside a building, there are so many paths for the lightning to take, it is unlikely that you can do anything quickly to fix it. Surge arrestors on incoming telephone, power, generator lines will help; multiple layers of protection (second set, finer grade) at the panelboards will filter out even more.
If you don't do these things, have sacrificial components and spares. Usually that is easier...
Re:Fiber (Score:2)
That type is controversial. Vendors and anecdotal evidence insist that they work. Competing vendors and physics-based calculations insist that they don't.
>Once you are inside a building, there are so many paths for the lightning to take, it is unlikely that you can do anything quickly to fix it.
Provide it a better path, outside the building. That would be a short, thick, *straight* run of copper to a good earth ground.
Re:Fiber (Score:2)
College campus with approx 14 buildings, spread out over a distance from each other. All buildings are home run back to a central building which serves as the fiber aggregate.
Lightning struck a tree, approx 30 feet from one building, approx 100 feet from another. The bolt spiraled down (nice bark pattern from where the bark got blown off, and the bark was smooth enough some of us used it wet as skates), dug into ground, and scattered all directions. The building
Re:Some real advise (Score:2)
A single-point ground is preferred; to have multiple grounds can set up what is known as a "ground loop" -- you can end up with current flow through your shield if the ground at one end is at a different potential than the ground at the other end. This current can induce unwanted noise in your signal lines. If the potential difference is great enough, damage may res
Lighting tips (Score:4, Informative)
As a said, in a direct strike, you're pretty much screwed no matter what. Indirect strikes can induce very high voltages, since they give off a pretty good EMP. It's extra-important to surge-protect the long runs of cable. You don't need to lay new cable, just install surge protectors at both ends of the run.
Buy cheap networking equipment, and keep money to replace it on hand.
Re:Lighting tips (Score:3, Interesting)
We use substation-class arrestors to protect or industrial motion controls from direct strikes. Not cheap, you're right, but they do work.
Something else to keep in mind is that unless you're talking about spark-gap or gas discharge type arrestors (i.e. anything like that will be SPECIFICALLY mentioned on the box), you're dealing with Metal Oxide Varistors (MOVs) and the protection should be REPLACED after every major storm since you cannot practically test if the MOVs will clamp properly again. The only
Re:Lighting tips (Score:1)
Re:Lighting tips (Score:2)
The current from lightning is about 10 kilo amps. The voltage is described as several hundred million volts. Let's say 500E6 volts.
Ohms law E=IR, or R=E/I solving for R.
R = 500E6 / 10000 = 50,000 ohms
Re:Lighting tips (Score:3, Informative)
Re:Lighting tips (Score:1)
You can't get around Ohm's law. I don't know about you, but around MY house, we obey the laws of nature.
R = E/I. If there is no current flowing, the I is Zero, and R is undefined. If the air is ionized, then current is flowing, and R is 50K ohms.
So to say what the resistance of air would be before the air is ionized and current is flowing is nonsensical. When you say teraohms or petaohms, I wonder how you got those numbers. And why those numbers, and not exaoh
Re:Lighting tips (Score:2)
I agree though, the resistance is so high as to be nonsensical. After all, quality film caps already have resistance in the order of gigaohms, and the dielectric is some millionths of an inch thick.
Re:Lighting tips (Score:2, Informative)
For an insulator such as air, you must look at its dielectric strength as well as the distance. From this, you can calculate the breakdown voltage required to generate an arc. For air, I believe it's roughly 10,000 V / inch. Of course, this depends on factors such as humidity, temperature, pressure, gas compos
Lighting, eh? (Score:2)
Thomas Edison was a Genius!! Lighting through air. So much better than lighting through wood.
I recommend the new low-power LED lighting. It's expensive, but it's mega-awesome.
Re:Lighting tips (Score:2, Informative)
Re:Lighting tips (Score:2)
Good, good.
Add one more vital point. There must be only one ground connection for all of the incoming wires. During a nearby or direct strike, two ground rods a few meters apart may temporarily be thousands of volts apart. If the surge protector for your phone is on one of those and the protector for the network is on another, well, bo
Monsoon? Yer lucky... (Score:2)
Still, it's kind of neat to have one of these storms in
Re:Monsoon? Yer lucky... (Score:2)
Howdy neighbour (Score:2)
Just listened to CBC on the way home from work - we have about 20 cm on the ground now, another 20 by tomorrow. Branches all over the place, power out, TransCanada closed... crazy, man, crazy.
Of course the farmers are loving it, and I can't blame them. About time we got some moisture into the ground. Lots of nitrogen, too. I can't complain. Besides, it gives me an excuse to stay in tonight and watch Calgary kick ass!
APC makes inexpensive products for this (Score:5, Informative)
A 1U rack mount chassis with 24 slots (you can protect up to 16 data lines) is $30. Then you can buy different plug-in modules for different devices. They have them for 10/100BaseT, regular Telco phone lines, T1/ISDN/etc, RS232, etc.
Get one of these [apc.com] for $18 per Cat5 you want to protect.
Keep in mind that nothing is going to protect against a direct lightning strike, but these are good filters for surges that can come from an indirect hit.
Re:APC makes inexpensive products for this (Score:2)
C'mon man, everybody knows Perfect Circle makes piston rings.
10BASE5... new? (Score:3, Funny)
Re:10BASE5... new? (Score:1)
not even 10 years ago, but i suppose in techterms that should be enough to me me feel old...
Re:10BASE5... new? (Score:1)
simple physics (Score:1, Funny)
come on
"excuse me but we in bangladesh were wondering if you could ever so kindly sho us how to do a hip replacement?
Cheapest solution (Score:2)
Twenty years ago... (Score:2)
But he eventually bought a locally made UPS. He said it was noisy, making hissing and spitting noises. But it worked great.
Well, that was twenty years a
Re:Twenty years ago... (Score:2)
Dude, not much has changed
Cheap man's lightning rod (Score:2, Funny)
Grounding! not devices (Score:3, Insightful)
You can get arrestors for 10base2 and 10base5. These should be installed on every building, near the electrical service panel (entrance) and tied to the building electrical ground stake. I think you still have those with ring-mains. Use as short and as fat a wire as possible -- impedence matters.
10baseT and 100baseTX should never be run inter-building and arrestors for it are hard to find. Beware the cute little cubes in userspace -- they have a long ground return path which presents high impedence, forcing more of the surge through active components.
Make sure all your computers have three-prong plugs.
Re:Grounding! not devices (Score:2)
On grounding and lightning rods (Score:3, Informative)
It's assumed that the equipment is connected to surge protectors on the power line; I believe the original poster was wanting to protect the network cabling from lightning strike.
By far, the most important thing to do is grounding (o
Re:On grounding and lightning rods (Score:2)
As for a lightning rod, you are quite correct that they need to be near the building being protected. Since the lightning
Re:One ground one end of 10base2 or 10base5 (Score:2)
With interbuilding cables, only earth-ground one end of the shield. Earth potential can vary by several hundred volts between buildings, even without the storms. If you ground both ends, you are creating a dangerous high voltage ground loop.
Fiber is definitly one of the best solutions for eliminating ground loops on inter-building runs.
Opto-isolate? (Score:2)
One Word.... (Score:2, Informative)
Fiber.... Get a two fiber to 10baseT, 10Base5, 10Basew2, 100BaseT or 1000BaseT transeivers. Lightining doesn't really impact fiber. Then use fiber for the long haul...
OR
you can buy 4 Fiber transeivers and a two, 1 meter fiber patch cords and put 2 transeivers on either end and use it kind of like a optical isolator. then if lightining hits the transport copper you, at most lose 2 transeivers, and the networks on either end are ok. Then all you should have to do is replace the 2 transeivers on either end.
Re:One Word.... (Score:2)
Re:One Word.... (Score:1)
You will need some form of circuit isolation for the powered transeivers on each end. A really good power bar.. or UPS will probably do it for you. And you should plug it into a completly different electrical circuit from the rest of your network, if you can..
An option. (Score:2)
Re: (Score:2, Funny)
You can't protect a network adequately (Score:1)
Quality surge protection on everything. (Score:1)
We installed 3 printers, 6 PC's, and 1 server at a client. The next day, the pole outside got hit by lighting. The electricty burned the CAT 5 in the walls and smoked all the PC's and printers. The server survived, all it needed was a new NIC.
Insurance paid us to do the job all over again...
Make it about money (Score:2)
Arresters typically come with insurance; if the protection fails to protect, they pay you. If this fails to catch your PHBs's attention, start wearing a scuba diving outfit to work and tell them that the rubber is to prevent you from getting killed by the lightning, and oh, by the way, would they mind very much if you took out life ins
Optics and gas discharges (Score:2)
I once worked for a telcomms comapny which amongst other things made most of the surge arresotrs used in Italian exchanges.
What I learned is that despite the fact that there are very many different solutions around, the simple and very effective solution uses a gas discharge device in paralell with a transorb (bi-directional zener). The transorb is very fast and has a high voltage, it briefly protects the l
Hopefully, you can't (Score:1, Insightful)
Gronding is key (Score:2, Informative)
10Base5 ok (Score:2)
10Base5 was designed for running between buildings. If at all possible you should use fiber for that job, but if facing the choice of which segment to replace, get rid of all the 10Bast2 and 10(0)BaseT NOW.
Ground loops are a far more likely problem than lightening, and only 10Base5 has any protection for that. (and then only if your transceivers are designed correctly...)
Even still glass fiber is the only way to go. I'm just giving you a priority of replacing things.
Firsthand seen lightning problems. (Score:1)
the lightning hit the electrical mains (the meter + main breaker on the exterior of the house), which happens to have the POTS POP 6 inches away.
they had to replace nearly every electrical device in their house.
At my own home, i recently discovered that I've been running 15A worth of computer equipment (boxes, monitors, net gear, etc) on an UNGROUNDED line. (house wiring ci
The way I did it (Score:2)
---Ethernet Lead 1 - MOV - 1A Fuse -\
---Ethernet Lead 2 - MOV - 1A Fuse --\
---Ethernet Lead 3 - MOV - 1A Fuse ---\
---Ethernet Lead 4 - MOV - 1A Fuse ----\
---Ethernet Lead 5 - MOV - 1A Fuse ----- Ground
---Ethernet Lead 6 - MOV - 1A Fuse ----/
---Ethernet Lead 7 - MOV - 1A Fuse --